Explosive energy transfer system

ABSTRACT

A flexible, hermetically sealed, explosive-energy transfer system adapted to trigger an explosive device in an environment which is hostile to combustion comprising a mild detonating fuse surrounded by a flexible, gas-impervious bellows which is encased in a sheath. The bellows and sheath are sealed to end fittings.

United States Patent [191 Alchorn et al. 1 Dec. 3, 1974 EXPLOSIVE ENERGY TRANSFER SYSTEM 3,362,290 l/19.68 Carr et al 102/49.5

3,6222, m2 Tessie: mac 2 Werner A. Gans, Sunnyvale; William D. Mellana, Santa Cruz, all of Cahf Primary E.\'aminer--Verlin R. Pendergrass [73] Assignee: The United State of Ameri a a Attorney, Agent, or Firm-R. S. Sciascia; P. Schneider represented by the Secretary of the Navy, Washington, DC.

22 F1 d: D 13, 1973 1 ec 57 ABSTRACT [21] Appl. No.: 424,522

g -A flexible, hermetically sealed, explosive-energy trans- [52] US. Cl. 102/27 R, 102/70 R, 89/1 B fer system adapted to trigger an explosive device in an [51] Int. Cl. C06c 5/04 n ir nmen whi h is ho tile to combustion compris- [58] Field of Search. 102/27, 70; 89/1 B ng a mil n ing f surrounded y a i gas-impervious bellows which is encased in a sheath. [56] References Cited The bellows and sheath are sealed to end fittings.

UNITED STATES PATENTS 3,129,663 4/1964 Schnepfe, Jr. 102/27 12 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION The present invention relates to explosive energy transfer systems, and, more particularly, to an explosive-energy transfer system adapted for use in an environment which is hostile to combustion.

Advancing technology has required that many devices be adapted for use in hitherto hostile environments. One example of such adaptation is the deployment of rockets and missles for use on submarines. Other examples are readily identifiable in the field of outerspace weaponry.

In addition to the hostile aerospace environment, the extremely tight space and weight limitations which exist for all aerospace vehicles place severe demands on all systems used in such aerospace applications. Reliability is of primary importance in this field.

Known explosive energy transfer systems which use fuses as the detonating means have disadvantages which militate against their use in either aerospace, ground or undersea weaponry. These systems have several disadvantages which have inhibited use in such applications: the products of combustion must be contained; any discontinuity may interrupt the chain at combustion thus making them sensitive to mishandling and difficult to adapt to the tortuous path required for installation on board aerospace vehicles.

Existing explosive-energy transfer systems overcome some of the above drawbacks, e.g., Selvidge, US. Pat. No. 2,498,050, provides a flexible fulminating fuse and Barr et al, U.S. Pat. No. 3,106,131, show a cartridgeactuated device wherein products of combustion are contained. However, so far as applicant is aware, there is apparently no device which provides an explosive energy transfer system which is both flexible and completely sealed in such a manner as to adapt the same for use in an environment which is hostile to combustion.

The present invention overcomes the abovementioned disadvantages and provides a reliable explosive energy transfor system adapted for use in an environment which is hostile to combustion.

BRIEF SUMMARY Briefly, the present invention is a flexible, sealed, explosive-energy transfer system adapted to trigger an explosive device in an environment which is hostile to combustion, comprising an elongated mild detonation fuse surrounded by a flexible gas-impervious bellows which is encased within a sheath. End fittings attached to the ends of the bellows and sheath by sealing means, such as welded or brazed joints, are used to connect the energy transfer system to other system components.

The flexible convoluted bellows is an important feature of this invention because it, along with the braided sheath, provides versatility to the device. The bellows protects the mild detonating fuse and allows the fuse to be routed over a tortuous path without breaking the fuse. The bellows also contains the pressure developed during combustion of the fuse. The sheath provides support strength to the bellows to resist shock and pressure generated by combustion of the mild detonating fuse and aids in furnishing complete containment of the detonation products without hindering flexibility of the bellows. Because ofthis, the bellows can be made more flexible than one without the added support provided by the sheath. The end fittings and sealing means insure a complete hermetic seal to the system.

In its more specific aspects, the bellows may be made from thin stainless steel which is covered by a braided, stainless steel sheath.

Among the objects of the invention are: to provide an improved explosive-energy transfer system suitable for use in an environment which is hostile to combustion.

and to provide. for use in aerospace and undersea control and actuation-event applicants, a completely contained explosive-energy transfer system which is hermetically sealed to protect it from adverse environments while providing a high degree of flexibility.

Other objects, features and advantages will appear from a reading of the following description in conjunction with a single FIGURE of the drawing which illustrates a partially cut-away side view of the explosive energy transfer system of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the FIGURE, the explosive energy transfer system 10 of the invention comprises a flexible bellows l8 encased in a flexible sheath 20 which may be of braided steel and provides strength and support to the bellows. The bellows is hermetically sealed to end fittings 22 by attaching means 24. Within the bellows, there is a mild detonating fuse l2 (MDF) constituted by an elongated cylindrical tube 14 which encloses a detonating or deflagrating material 16.

The mild detonating fuse 12 is used to initiate an explosive Booster Charge such as is shown by numeral 32. The tube 14 provides containment and protection to the explosive material 16 and encases the material for substantially the entire length thereof. Tube 14 may be fabricated of metal, such as aluminum, or any other durable material having similar mechanical characteristies.

In aerospace and undersea application, mechanical integrity of MDF 12 is of major importance. Therefore, more protection than is provided by the tube 14 alone must be provided for an MDF used in hostile environmental conditions and subjected to great mechanical demands.

Such additional protection and flexibility is provided by the flexible belllows l8 encased within the sheath 20 and sealed by attaching means 24. The bellows is preferably of corrugated design having peaks 28 and valleys 30 and surrounds the MDF 12 for a length sufficient to adequately protect the MDlF under the requirements imposed thereon and provide desired flexibility. The length of the MDF which is to be covered by he]- lows 18 is determined by the expected environmental conditions as well as the anticipated mechanical requirements. As will be discussed below, end fittings 22 and attaching means 24 encase the MDF for some length thereof and thus affect the distance with which bellows l8 surrounds the MDF. However, in the preferred embodiment, the bellows will surround the fuse for an appreciable portion thereof. This insures protection for the fuse. and containment of the system.

Bellows 18 is impervious to gas and is constructed of any durable, flexible material, preferably stainless steel. Copper or mild steel can also be used. The bellows is gas-impervious to maintain the required hermetic seal when the energy transfer system is used in hostile environments. The bellows contains the gases generated by the combustion of the MDF. When the energy transfer system is used in aerospace, ground or undersea applications, it is obviously undesirable to allow products of combustion to contaminate the space or undersea vehicle containing the energy transfer system. More than mere undesirability is involved if the products of combustion themselves are secondarily explosive. The obvious dangers involved in this situation need no further discussion.

The wall thickness of the material used to fabricate the bellows is primarily selected according to the degree of flexibility desired and the loads imposed on the energy transfer system. In many applications, space requirements are severe. This is especially true in the aerospace applications wherein the maximum amount of payload is placed in the minimum amount of vehicle space. Therefore, in many applications, the energy transfer system will be forced to take a tortuous route between actuating means and actuated means. Thus, the flexibility of the energy transfer system is selected to provided ease of installation as well as to provide mechanical protection to the MDF to assure the continuity of explosive material 16. As above discussed, any break in explosive material 16 may disrupt the combustion of the'MDF and destroy the reliability of this system. The wall thickness of bellows 18 is selected to allow flexibility while still providing structural strength for the fuse. in the preferred embodiment, this thickness varies between one and three mils. The upper limit is determined according to the degree of flexibility required for the fuse and the lower limit is selected according to the amount of pressure generated by detonation of the MDF. The bellows wall thickness must be sufficient to withstand such pressure without rupturing.

The wall thickness of bellows l8 and sheath 20 combined is also selected according to desired outside overall diameterforthe system. This overall diameter may be as low as three-eighths of an inch depending on the application.

The wallthickness of bellows 18 may be selected to allow permanent deformation of said bellows if the energy transfer system is mishandled. Thus, visual indication is provided by a misshapen outer perimeter to warn of possible reduced system reliability due to maltreatment of the energy transfer system during shipping and/or storage of the energy transfer system which might result in a broken fuse.

In addition to providing mechanical protection for the MDF and flexibility to the energy transfer system, the bellows also controls the detonation efficiency of the explosive material 16. Pressure and temperature are two important variables in any combustion process. Control of both of these variables is important for the proper functioning of any energy transfer system. Bellows 18 provides such control.

Since the bellows I8 is impervious to gas, the pressure in the system is a function of internal volume. The bellows should be flexible, yet strong enough to withstand the pressure generated by the MDF.

In order to maintain system strength and durability while still allowing flexibility, the bellows is supported by a sheath 20 which provides support strength for the bellows to resist the shock and pressure generated by function of the MDF. The sheath also assures complete containment of the detonation products. The support added by sheath 20 achieves the required bellows flexibility without increasing the danger of rupturing the bellows due to internal pressure. The sheath 20 is fabricated of tough, flexible material such as stainless steel braid. The wall thickness of sheath 20 is such as to provide sufficient flexibility for ease of routing and installation while assuring a completely sealed system, as contrasted to rigid-tubing.

S heath 20 is positioned longitudinally about bellows 18. Preferably, the bellows is unattached to the sheath, but may contact the sheath if so desired. The spacing between the bellows and the sheath affects the amount of expansion of the bellows upon detonation of the MDF. By maintaining the bellows and sheath in close proximity expansion of said bellows is minimized. However, the preferred embodiment of the system maintains contact between the sheath and the bellows.

The energy transfer system is connected between detonating and detonated devices by means of scaled end fittings 22. As both end fittings 22 are identical in the embodiment shown in the drawing, this description will refer to only one of said fittings; however, it is equally applicable to all of the fittings used to connect this system to other system components.

The MDF is attached to the end fittings and is actuated by Booster Charge similar to the charge shown by the numeral 32 which is held in close proximity to a detonating device, or other system component by threaded nut 34. The MDF is attached to the end fitting by any commonly known means.

The ends of the bellows and sheath are joined to end fittings 22 by a welded or brazed joint 38 which serves to seal the end of bellows l8 and to attach the adjacent end of the sheath 20 neck portion 40 of the end fittings. The neck portion 40 is preferably integral with the rest of fitting 22; however this neck portion can be sealed to threaded nut 34 by any means which will satisfactorily produce a rugged, hermetic seal of the system will not be broken when the bellows-sheath portion thereof is flexed during handling or installation. The neck material is sufficiently strong to withstand the initial shock and pressure generated by the MDF upon actuation thereof. Joint 38 should have strength and sealing characteristics at least equivalent to those required for neck 40. As flexing the sheath bellows combination will place severe stress upon the joint 38, the tensile strength of the joint is important. The heat transfer characteristics of both the neck portion 40 and joint 38 are such as to allow disipation of any heat generated by the combustionof the MDF without melting or weakening the seal provided by joint 38.

A sleeve 42 at the end of the braided sheath 20 and bellows l8 assures proper hermetic sealing of the ends of the bellows to the sleeve at the location to the joint 38. The complete hermetic seal between the end fittings and the remainder of the energy transfer system allows the system to be safely and reliably actuated in environments which are hostile to combustion. The hermetic seal is also of sufficient tensile strength to insure that the energy transfer system will remain integral when the system is flexed and routed over a tortuous path in small vehicles such as those commonly used in aerospace, ground or undersea applications.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than specifically described.

What is claimed is:

1. An explosive-energy transfer system adapted to trigger an explosive device, comprising:

a mild detonating fuse;

a gas-impervious bellows surrounding said fuse in a longitudinal direction for an appreciable portion of the length thereof, said bellows being flexible in all directions;

a flexible sheath encasing said bellows and positioned longitudinally about said bellows in close proximity thereto;

end fittings for said bellows and sheath; and

means for hermetically sealing said bellows to said end fittings,

the flexibility of said bellows and sheath enabling the explosive energy to be routed over a tortuous path.

2. An explosive-energy transfer system adapted to trigger an explosive device, comprising:

a mild detonating fuse,

a gas-impervious corrugated bellows surrounding said fuse in the longitudinal direction for a major portion of the length thereof;

a flexible braided sheath encasing and contacting the corrugations of said bellows;

end fittings for said bellows and sheath; and

means for hermetically sealing said bellows to said end fittings.

3. An explosive-energy transfer system as recited in claim I, wherein the bellows and the sheath are stainless steel.

4. An explosive-energy transfer system as in claim 1 wherein the sealing means includes a welded joint.

5. An explosive-energy transfer system as recited in claim 1 wherein the sealing means includes a brazed 6 joint.

6. An explosive-energy transfer system as recited in claim 1 wherein the mild detonating fuse comprises a cylindrical explosive material and a metal tube surrounding said explosive material for substantially the entire length thereof.

7. An explosive-energy transfer system as recited in claim 1 wherein the sheath is impervious to detonation products.

8. An explosive-energy transfer system as recited in claim 1 wherein the bellows and sheath is metal and is braided.

9. An explosive-energy transfer system as recited in claim 2, wherein the bellows and the sheath are stainless steel.

10. An explosive-energy transfer system as in claim 2, wherein the sealing means includes a welded joint.

11. An explosive-energy transfer system as recited in claim 2, wherein the mild detonating fuse comprises a cylindrical explosive material and a metal tube surrounding said explosive material for substantially the entire length thereof.

12. An explosive-energy transfer system adapted to trigger an explosive device comprising:

a mild detonating fuse;

a gas-impervious corrugated bellows surrounding said fuse in a longitudinal direction for an appreciable portion of the length thereof, said bellows being flexible in all directions;

a flexible sheath encasing said bellows and positioned longitudinally about said bellows in close proximity thereto;

end fittings for said bellows and sheath; and

means for hermetically sealing said bellows to said end fittings. 

1. An explosive-energy transfer system adapted to trigger an explosive device, comprising: a mild detonating fuse; a gas-impervious bellows surrounding said fuse in a longitudinal direction for an appreciable portion of the length thereof, said bellows being flexible in all directions; a flexible sheath encasing said bellows and positioned longitudinally about said bellows in close proximity thereto; end fittings for said bellows and sheath; and means for hermetically sealing said bellows to said end fittings, the flexibility of said bellows and sheath enabling the explosive energy to be routed over a tortuous path.
 2. An explosive-energy transfer system adapted to trigger an explosive device, comprising: a mild detonating fuse; a gas-impervious corrugated bellows surrounding said fuse in the longitudinal direction for a major portion of the length thereof; a flexible braided sheath encasing and contacting the corrugations of said bellows; end fittings for said bellows and sheath; and means for hermetically sealing said bellows to said end fittings.
 3. An explosive-energy transfer system as recited in claim 1, wherein the bellows and the sheath are stainless steel.
 4. An explosive-energy transfer system as in claIm 1 wherein the sealing means includes a welded joint.
 5. An explosive-energy transfer system as recited in claim 1 wherein the sealing means includes a brazed joint.
 6. An explosive-energy transfer system as recited in claim 1 wherein the mild detonating fuse comprises a cylindrical explosive material and a metal tube surrounding said explosive material for substantially the entire length thereof.
 7. An explosive-energy transfer system as recited in claim 1 wherein the sheath is impervious to detonation products.
 8. An explosive-energy transfer system as recited in claim 1 wherein the bellows and sheath is metal and is braided.
 9. An explosive-energy transfer system as recited in claim 2, wherein the bellows and the sheath are stainless steel.
 10. An explosive-energy transfer system as in claim 2, wherein the sealing means includes a welded joint.
 11. An explosive-energy transfer system as recited in claim 2, wherein the mild detonating fuse comprises a cylindrical explosive material and a metal tube surrounding said explosive material for substantially the entire length thereof.
 12. An explosive-energy transfer system adapted to trigger an explosive device comprising: a mild detonating fuse; a gas-impervious corrugated bellows surrounding said fuse in a longitudinal direction for an appreciable portion of the length thereof, said bellows being flexible in all directions; a flexible sheath encasing said bellows and positioned longitudinally about said bellows in close proximity thereto; end fittings for said bellows and sheath; and means for hermetically sealing said bellows to said end fittings. 